Lock-stitch sewing machine



Nov. 13 1923. 1,474,138

F. J. T. BELL ET AL LOCK STITCH SEWING MACHINE Filed July 12, 1920 5 Sheets$heet 1 Nov. 13 1923.

F. J. T. BELL ET AL LOCK STITCH SEWING MACHINE Filed July 12'. 1920 3 Sheets-Sheet 3 Nov. 13 1923. 1,474,138 F. J. T. BELL ET AL LOCK STITCH SEWING MACHINE Filed July 12. 1920 5 Sheets-Sheet 3 I Ire; fo we;

MMWMQ Patented Nev, 1%, i923.

tli lllTElE S FREDERICK JOE-IN TURNER BELL AND HARDY CECIL BELL, 0F MOSSLEY, ENGLAND.

LOCK-STITCH $EWING MACHINE.

Application filed July 12,

T0 (ZZZ whom it may concern.

Be it known that we. F REDEBICK JorIN TURNER BELL and HARDY CncIL BELL, both subjects of the King of Great Britain and Ireland, and both residing at Castlewood Place, Moseley, in the county of Lancaster, England, have invented certain new and useful Improvements in and Relating to Lock- Stitch Sewing Machines, of which the fol lowing is a specification.

This invention relates to lock stitch sewing machines, (in which machines a rotating or oscillating hook passes the needle thread loop around the underthread and the loop is pulled up to form the stitch), and particularly to that type of such machine known. as the two-reel, wherein a bobbin, cheese, or the likehereinafter referred to as a bobbin-is used for the underthread in the form in which it comes from the manufacturer, thus dispensing with preliminary spooling. The invention can however be applied to a machine the underthread in which has been rewound, say on to a spool, before use.

The object of the invention is to provide improved mechanism whereby the following advances in the art may be obtained, viz: a minimum of tension on the needle thread loop as it passes over the casing contain ing the bobbin of underthread; the elimination of all danger of spoiling the goods being machined by the contact of the thread with lubricating oil; the provision of means whereby the empty underthread bobbin may 3e projected centrally from the bobbin casing so that the operator may remove it without trouble or fumbling; and the adaptation of the two-reel principle to hand machines by a reduction of the vertical height hitherto necessary for the accommodation under the machine table, of hitherto proposed two-reel lockstitch mechanism.

lVith the above in view, our invention consists of a rotating or oscillating plate carrying a, hook for engagement with the needle thread loop, said plate entirely supporting and having movement around a disc or the like into which disc the casing for the bobbin of underthread is fitted. To adaptthe mechanism to hand sewing niachines wherein the vertical space available for the stitch forming mechanism under the machine table is of necessity limited, we may arrange the hook carrying plate with its axis considerably inclined to the ver- 1920. Serial No. 395,509.

tical, and the bobbin casing may also be inclined to the vertical with its upper open end pointing towards the operator, for the speedy withdrawal of an empty bobbin and its replacement by a full one. The bobbin casing may however be vertical. Such inclined parts are described in the following specification and shown in the accompany ing drawings, but it will be understood that we do not confine ourselves to any particular angle for the hook carrying plate and bobbin casing. In order to facilitate the speedy withdrawal of a bobbin from the casing we provide a central holder in the casing but having spring means, hereinafter fully described, for holding down the bobbin, and which spring means being released by the operators finger project the bobbin well out of the casing so that the bobbin may be easily seized and removed.

Special driving means are also provided for an oscillating hook, when the latter is fitted at an angle to the vertical as referred to above, said driving means consisting of a wheel pivoted on the underside of the chine table, the axis of this wheel being in the same plane as the axis of the hook carrying plate and the said wheel, which is given an oscillating motion, being connected to the hook carrying plate by chains or the like to impart the oscillating motion to the latter.

We will now describe fully a method of carrying our invention into effect in a lockstitch. machine of the oscillating type, with the lockstitch mechanism fitted into the smallest practicable vertical space, and adapted for the use, as uiiderthread, of a bobbin or". thread it comes from the manufacturen' The description will be given'with reference to the accompanying drawings, in which i Figure 1 is an elevation of the stitch forming mechanism viewed from the needle end of the machine;

Figure 2 is a plan of Figure 1;

Figure 3 is an elevation of the mechanism from the back of themachine, that is, at right angles to Figure 1.

Figure 4 is an elevationof the bobbin casing and its supporting plate, the hook carrying plate being removed;

Figure 5 is a plan thereof;

Figure 6 is a se tion showing the details of holder for the bobbin in the bobbin casing and the parts which permit of the partial ejectment of the bobbin;

Figure 7 is a bottom view of the sewing machine bedplate, showing our special drive for an inclined hook carrying plate as illus trated in Figures 1, 2, and 8; and

Figure 8 is a cross section on line YY of Figure 7.

Figures 1 to 6 are about double actual size; Figures 7 and 8 half actual size.

Referring to Figures 1, 2, and 3, 1 is the needle, 2' is a bracket fixed to the underside of the sewing'machine bed plate, said bracket having an inclined arm 3 bearing a pivot 4 on which the conical casing 5 isadapted to rotate. This conical casing may have part of its sides cut away as shown in Figure 3 to secure the minimum of weight, and it is formed warm annular base'b as shown, and which base has an internal annular recess 6. Part of the base is cut away to form a loop taking hook 7 This hook'will for conveniencebe hereinafter referred to as the hook, and the conical casing 5' with annular base 6 will be referred to as the hook'plate'. 8 is a flat disc the edge of which fits in the recess 6 of the hook plate and forms a race for the said hook plate. In this disc is fitted a bobbin casing 9 adapted to receive a bobbin of underthread on the holder 22, the said bobbin casing being provided ribs 10, 11, and 12 "approximately'in the positions shown, the rib'lO being of greater dimensions than the others. The race'plate 8 is cut away at 13, 1 1, the cut away or recessed parts forming stops in combination with the ends 17 and 18' of a spring TGfiXQCl on an anchoring device 15, to allow the plate 8 a slight oscillatory movement only around its axis.

The Figures 4 and 5 show clearly the formation of this disc 8 and the parts just described;

The process of forming the stitch is as follows :--The hook 7 on the hook plate 5 being at point i of Figure 2, which is its loop takingposition, the hook plate 5moves and one'side'ofthe needle thread loop e11- its "casting or position 2' the take up of the machine comes intoa'ction, and pullsthe side of the loop between recess 14 and'point 18. Both sides of the", loop are now behind the bobbin casing 9 'and' afre'pulled up over the undert'hread' to form the stit ch as usual.

The race plate'8 being entirely supported by the hook plate 5, it follows that the triotionbetween them will tend to pull the plate 8 in the direction of movement of the hook plate and there is therefore a certainty of the necessary space being left between 13 and 17 for the/passage of that side of the needle thread loop when the hook 7 commences its oscillation. lVhen the take up commences to pull up the stitch, the hook 7 has just commenced its return from point 2 to point y, and the drag on the plate 8 consequent thereupon will open the passage or the side of the needle thread loop passing between points 14 and 18,

19 is a plate spring secured to the side of rib 11 by means of screw 20, between which spring and rib the underthread from the bobbin casing 9 is passed to the working point of the machine. The tension of the spring may be regulated by adjusting the screw 20, the whole forming a simple and effective underthread tensioning device.

The race plate 8 may be cut away at 21 21 to reduce its weight as much as possible (Figures 1 and 5).

The special holder or pin for the bobbin in the bobbin casing 9 is shown in detail in Figure 6. In that figure 22, is a tubular holder, and 23 23 are'springs fixed thereon to retainby friction the bobbin placed thereon, as is usual. 2 1 is a tubular spindle secured by any convenient means in the bottom of the casing 9, and which holds in position the helical spring 25, the upper end of which abuts on a shoulder formed within the'o'uter tube 22. 26 is a tubular part, internally screwed to fit on the spindle 2e and having pivoted at its upper end the arm 27 of formation as shown. 28 is a helical spring fitting within the spindle 2 4, abutting on the bottom of this hollow spindle at the lower end and at its upper end against the underside ofthe cheese head 30 of a pin 29. As shown in the figure, the parts are in the position they will assume when a bobbin is fitted on the outer tube 22, being held down by the arm 27. When the bobbin is to be removed, the arm 27 is merely flicked to a vertical position with the finger, and is held in that position by the pressure of the head of pin 29 on the end of arm 27. The spring 25 is thus free to act, and pushes against th internal shoulder of the outer tube 22, which is thus pushed up, carrying the bobbin with it, the end of the bobbin projecting centrally from the bobbin casing sutficiently to enable theoperator towithdraw it easily. A new bobbinbeing put on the holder 22, the arm 27 is depressed, to the position shown in Figure 6, and the bobbin is thus securely held until the lifting of the arm 27 by the operator releases it. 1

The special driving means for a hook plate inclined to the vertical, as shown in Figures 1, 2, and 3, are illustrated in Figures 7 and 8.

A vibrating arm 31, Figure 7, pivoted at 32 drives, through a lL k wheel 334 rotatably mounted on a boss 35 (Figure 8) on the bottom 01 the ma l ne bedplate. The wheel 34 has a @roov i periphery, and is formed with a recess a l as shown. Two chains, 36, 56 one end of each of which is pinned or otherwise conveniently secured in groove formed in a driving block 7 at the apex Or the hook plate 5 pass around the wheel 8 their other ends being brought with- 'n the nut 38 which is grooved on its upper -d lower faces to slide within the recess a to enable the chains 36, 36 to be tighteo up or slackened; Conveniently the nut is made in two parts, and the ends of chains 36. 36 to be secured therein are provided with rings. The nut is threaded for the reception of screw 39 which passes through both'halves of the split nut and through these rings, thus holding the chain ends securel in the nut and at the same time allowing for the tightening up ofthe two halves of the nut to hold it securely by friction at any point in the recess 343-. Any other convenient means of securing the ends of the chains 36, 36 and to render them adjustable, may-be however adopted.

It will be seen that the improved stitch forming mechanism described above may be equally well applied to a rotary lock-stitch sewing machine. In this case however it will be necessary to time the take up action of the machine to commence its take up movement before the hook 7 reaches the point a of Figure 2, and the particular formation of the hook will allow of this. The stitch beingthus drawn up, the hook 7 may continue its journey around the back of the bobbin casing 9 and by complete rotation return to the loop taking point y to take the hex loop. For a rotary hook also the special driving means hereinbefore described will be dispensed with, and an undershaft as commonly used may be substituted therefor, said undershatt bearing on the end thereof a worm meshing with a wheel fitted to the apex of conical casing 5 and taking the place or" the driving block 3?.

VJ e do not confine ourselves to the details shown in the drawings and described above, as they may be varied without departing from the spirit of our invention.

We claim 1. Lock stitch mechanism for a sewing machine, comprising a hook plate carrying a loop taking hook to engage the needle thread loop, a plate surrounded by and entirely supported by the said hoox late and iormin a race there-for, an underthread bobbin casing titted within said race plate, the hook plate having an axis of rotation inclined to the vertical and the bobbin casing being also inclined to the vertical and inclined at an angle to the axis of the hook plate with its upper open end towards the operators side of the machine and driving means for the hook plate comprising a wheel pivotingon the lower side or" the machine bedplate and having an oscillatory motion; a driving block secured to the hook plate, and connections between said wheel and said driving block to communicate the oscillations of the to "iner to the latter.

2. Lock stitch mechanism for a sewing machine, comprising a hook plate carrying a loop taking hook, a bobbin casing for the underthread over which casing the needle thread loop passes, the hook plate being adapted to oscillate around an axis inclined to the vertical, said bobbin casing having its axis inclined to the axis of the hook plate, and driving means for the hook plate comprising a wheel pivoting on the lower side of the machine bedplate and given an oscillatory motion, a driving block secured to the hook plate, and connections between the said wheel and said driving block to communicate the oscillations of the former to the latter.

3. Lock stitch mechanism for a sewing machine, comprising a hook plate carrying a loop taking hook, a bobbin casing for the underthread over which casing the needle thread loop passes the hook plate being adapted to oscillate around an axis inclined to the vertical, said bobbin casing having its axis inclined to the axis of the hook plate, driving means for the hook plate, said means comprising a wheel pivoted on the lower side of the machine bedplate and given an oscillatory motion, a driving block secured to the hook plate, chains connecting the said wheel and said driving block to communicate to the latter the oscillations of the former, and adjustable securing means for securing the ends or" the chains in the wheel.

In witness whereof we have hereunto set our hands.

FREDERICK JOHN TURNER BELL.

HARDY CECIL BELL. 

